<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .box {
        display: flex;
        height: 50px;
        width: 50px;
        background-color: #f6f6f6;
        flex-direction: column;
    }
</style>

<body>
    <div class="box">
        <div class="box1">1</div>
        <div class="box2">2</div>

    </div>
</body>

</html>